The present invention relates to a medical puncturing device e.g. for use in connection with the insertion of a soft cannula where the soft cannula e.g. forms part of a infusion device for subcutaneous delivery of a medication or a therapeutic fluid by means of an external infusion system and more particularly to a medical puncturing device capable of being discarded without the danger of causing unintended harmful injuries to persons afterwards.
The medical puncturing device will in the following be explained in connection with the field of subcutaneous infusion devices. Such infusion devices are generally known in the art for delivering a medication or a therapeutic fluid to a subcutaneous site in a patient. Such devices commonly comprise a soft tubular cannula extending from a housing adapted to receive the desired medication via means, e.g. disconnectable means, for suitable connection to further components of the infusion system. The possibility of disconnecting the infusion set from the further parts of the infusion system is provided in order to improve the user comfort. In order to place the soft cannula at a subcutaneous delivery site, a medical puncturing device comprising a rigid needle and a handle is used. The rigid needle is inserted through the hollow soft cannula and extends beyond the outer tip of this. The soft cannula is inserted into the subcutaneous fat layer of the patient together with the rigid needle, which is afterwards withdrawn leaving the soft cannula at the infusion site. In order to provide such disconnectable medical puncturing device and still maintain a fluid-tight sealing towards the interior of the housing and the tubular cannula that prevents contamination of the infusion site, such devices are commonly provided with a self-sealing penetrable septum on the housing. Upon withdrawal of the needle from the septum this provides a fluid-tight sealing towards the interior of the housing. The septum and the needle further provides a fluid-tight sealing between the housing and the connector means when medication or therapeutic fluid is delivered to the patient from the external infusion system. Subcutaneous infusion devices of this generally known type are known from e.g. U.S. Pat. No. 5,522,803 to Teissen-Simony and U.S. Pat. No. 5,545,143 to Fischell.
The use of a medical puncturing device comprising a rigid needle may lead to some disadvantages during use of such device, viz, the potential danger of unintended exposure to the needle tip after the needle has been discarded.
A medical puncturing device of a type providing some remedy for these disadvantages is disclosed in U.S. Pat. No. 5,533,974. This previously known device comprises a rigid needle and a protector housing wherein a biasing element, a cam and a gripping element are provided in order to lock the protector housing in relation to the needle at the pointed tip of this.
A further device is disclosed in U.S. Pat. No. 5,279,591. This previously known device comprises a rigid needle and a protector housing wherein a resilient spring means is provided to block the needle tip upon sliding the protector housing to the needle tip.
A still further device is disclosed in WO 9305840. This previously known device comprises a rigid needle and a protector housing wherein a resilient guard element is provided to block the pointed needle tip upon sliding the protector housing to the needle tip. Means for limiting the sliding movement are provided hereby ensuring the position of the protector housing.
Although these previously known medical puncturing devices to some extent give a satisfactory result with respect to the prevention of unintended and harmful needle sticks they all have a complicated construction requiring a cumbersome assembling process.
For this reason there is a need for improvements in the field of medical puncturing devices, the improvements relating to providing a medical puncturing device having satisfactory properties particularly with respect to providing a medical puncturing device which can be dismantled and discarded without the risk of causing any injuries, and at the same time being of a simpler construction requiring less effort in the manufacturing process.
The infusion needle according to the invention remedies the above mentioned disadvantages and provides further advantages which will become apparent from the following description.